<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link rel="stylesheet" href="./index.css">
</head>

<body>
  <h1>你好</h1>
  <script src="./index.js"></script>
  <script>
    console.log(ccc);


    document.querySelector("h1").onclick = function() {
      console.log(1);
    }


    document.querySelector("h1").onclick = function() {
      console.log(2);
    }
  </script>
</body>

</html>